Material’s tensile strength can be improved by the presence of a body-centered cubic (BCC) phase, which is essential in highstrength applications and highly corrosive environments. Thus, synthesizing a BCC single-phase, equiatomic AlCoCrFeNi high-entropy alloy (HEA) feedstock particle using a highenergy mechanical alloying (HE-MA) method was investigated. The transient alloy particles were developed using a planetary mill at a constant rotational speed of 580 rpm employing milling times in the range of 4 to 24 hours. During the process, stearic acid of 3 wt.% of the precursor composition was used as a process-controlling agent (PCA). Two HE-MA manufacturing regimes were utilized: i) conventional (milling constituent elements simultaneously), and ii) sequential (progressive milling while adding elements in a certain order). In addition to the conventional method, a sequential regime was employed to develop FeNiCoCrAl, wherein individual elements were added every 4 hours to the starting/milled Fe + Ni mixture. Based on the results, the HE-MA FeNiCoCrAl showed a BCC single-phase formation after 24 hours, with no intermetallic or contamination traceability. Finally, a nanoindentation hardness measurement was carried out to support the observed phase transformation before and after the HE-MA process.

In the current work a nano-crystalline Ni-20Cr coating was developed on a boiler tube material by cold-spray process. The coating powder was synthesized in-house by mechanical milling using a planetary ball mill. The average crystallite size of the developed powder was calculated to be 10 nm. The crystallite size of the coating was found to be 18 nm, and hence the retention of nano-crystallinity in the coating was established. However the grain growth occurred to some extent, which may be due to temperature rise involved in the cold spray process. A detailed TEM analysis of coated samples before and after exposure to high temperature oxidation was carried out.

Ultra fine grain Fe-Si based coatings were synthesised by HVOF thermal spraying of nanostructured powders obtained from mechanical milling. Magnetic measurements revealed a soft magnetic character for all the coatings. Additions of boron, niobium and copper were investigated. The thermal stability and the evolution of the coercivity with temperature were observed to be remarkable.

The repair and quick geometrical changes of components and tools are currently the most important applications of laser build-up welding. Advanced laser technology permits the integration of the main process steps into one machining center for a very efficient and flexible manufacturing process. The solution presented in this paper consists of a 3axes CNC milling machine, in which a 3 kW Nd: YAG laser, a coaxial powder nozzle, and a digitizing system are integrated. All functions (data processing, laser process, powder feeding, and milling) are controlled by one CNC controller using specially developed software. In the first step the workpiece needs to be adjusted to the machine table. Then the contour of the damaged surface is determined by either an optical or mechanical digitizing system. Using the resulting data, a software system generates automatically the laser build-up strategy and the CNC programs for the laser and the milling processes. After laser free-forming, a raw piece with an oversize of 0.3 to 0.6 mm is made. From this geometry the end contour is milled with an accuracy of some 10 microns. This way the machine produces a completely finished tool.

This work concerns the production and use of aluminum oxide-NiCr dispersion powders for thermal spraying. It investigates the morphology and hardness of the powders and the microstructure and wear resistance of the resulting coatings. The powders are prepared by high energy ball milling and are used to produce oxide dispersion strengthened NiCr coatings via HVOF spraying. Among the key findings is that the powders are less homogeneous when milled with nanoscale aluminum oxide as are coating properties. Paper includes a German-language abstract.